Assays will be developed which will enable one to directly quantitate immunological interactions between a growing neoplasm and the host's immune system, using two rat mammary adenocarcinoma cultured cell lines as model systems. The effects of tumor-associated antigens and/or antibodies specific for these antigens upon immunological interactions will be investigated. The ultimate goal is to develop simple, quantitative means of determining the immunological involvement of a tumor-bearing host, for the purpose of allowing one to effectively and efficiently design and evaluate therapeutic programs.